Steam blanchers have long been used in the food processing industry to blanch or cook a continuous throughput of food product such as pasta, green peas, corn, beans and other processed food and vegetables. Uniformity and product integrity are paramount concerns in preparing food for human consumption. To advance the food product through the blancher in a gentle, non-destructive, manner, helical augers mounted within the water filled blancher tank have long been used. The auger is mounted within a cylindrical drum having a perforated steel screen skin which allows water to flow freely into the interior of the drum. Rotation of the drum gently advances food product from the tank inlet to the tank discharge end.
At one time, these augers were mounted on a central drive shaft and were driven directly by an engaged sprocket and motor. A central drive shaft, however, presented several problems. First, the extension of the drive shaft axially through the inlet end of the tank interfered with the introduction of food product into the cylindrical drum. Furthermore, food product coming into contact with the central shaft was subject to damage. In addition, experience showed that central drive shafts were prone to breakage.
Conventional blanchers have eliminated the breakage problem of the central drive shaft by mounting the helical auger flights on a central cylindrical core which extends through the inlet and outlet ends of the blancher tank to define cylindrical journals which are supported on two rotatable trunnions at each end. The cylindrical core is of sufficient diameter to allow the introduction of an infeed chute through the inlet journal. To allow the food product to pass into and exit from the cylindrical drum, the core is replaced at the inlet and outlet ends of the drum with a number of structural steel bars symmetrically spaced a distance from the rotational axis of the drum equal to the radius of the core. These bars provide admirable structural stiffness and do not interfere with the introduction of the infeed chute. Yet the bars, which rotate with the drum with respect to the infeed chute, continuously pass through the path of the infed food product. A certain significant proportion of food product comes in contact with these rotating bars and, if the food product is at all delicate, damage results.
What is needed is a blancher with a rotating auger which permits substantially unobstructed admission of food product into the drum and a resultant preservation of product integrity.